ES2718332T3 - Micro / nano structures of colloidal nanoparticles fixed on an electret substrate and manufacturing process of said micro / nano structures - Google Patents

Description

DESCRIPTION

Micro / nano structures of colloidal nanoparticles fixed on an electret substrate and manufacturing process of said micro / nano structures

The present invention relates to micro / nano structures that are presented in the form of a monolayer or multilayer assembly of colloidal nanoparticles fixed on an electret substrate, arranged in a compact manner, and to the manufacturing processes of these micro / nano structures.

Throughout the text "electret material" means any material capable of preserving, for at least a certain time, an electrical polarization induced by an electric field, after the cancellation of said electric field.

Throughout the text, colloidal nanoparticles are solid bodies, having at least one of the dimensions between 1 and 1,000 nm, which form a discrete phase dispersed in a continuous or dispersing medium of different constitution, without being dissolved by it. Colloidal nanoparticles can be especially colloidal nanocrystals.

Throughout the text, "charged" colloidal nanoparticle means any electrically charged colloidal nanoparticle capable of being trapped by the action of coulombic or electrophoretic forces by an electric field generated by motives of charges inscribed on the surface of an electret substrate.

Throughout the text, colloidal nanoparticle "polarizable neutral" means any colloidal nanoparticle neutral or almost electrically neutral, capable of being electrically polarized when subjected to the action of an external electric field, and capable of being trapped by the action of only dielectrophoretic forces by an electric field generated by motives of charges inscribed on the surface of an electret substrate.

The colloidal nanocrystals NaYF4 with hexagonal mesh and doped with lanthanides have already tested their great interest because of their ability to effectively convert a near-infrared radiation and low energy into a visible radiation of higher energy luminescence, knowing this type of conversion by the denomination of high conversion (in English upconversion) or elevator in terms of frequencies. In addition to the incentive provided by unique electrical properties such as narrow emission bands, durations of long excited states and a stable photonic response, the high conversion of NaYF4 colloidal nanocrystals doped with Ln3 + lanthanides have promising applications in the fields of solid lasers, of low-intensity infrared imaging, sensors, security marking, photovoltaic indicators and devices.

In order to take advantage of the optical properties of NaYF4 colloidal nanocrystals doped with lanthanides, several procedures have been developed to assemble the colloidal and micromotive nanocrystals on the surfaces. These procedures devoid of inscription of motifs of surface charges are, for example, the mechanical microcontact (pCP) combined with "inflated figures" by drops of water, the photoforming of motifs that use a chemical amplification reaction, the micromoldeo in capillary elements (MIMIC) using polystyrene spheres, colloidal lithography.

However, these procedures have the drawbacks according to which (i) the height of colloidal nanocrystal assemblies has not been precisely mastered or directed, (ii) the spatial resolution of the colloidal nanocrystal patterns created is limited, (iii) the geometries of the motifs are limited and include defects, (iv) the duration of the procedures is high, and (v) spatially controlled micromotives cannot be performed with two types of nanocrystals (binary assemblies).

For some years, AFM atomic force microscopy nanoxerography (Atomic Force Microscopy) has proven to be an innovative technique for the manufacture of surface mounted colloid assemblies.

This technique uses motifs of electric charges inscribed in electrets by an AFM tip to electrostatically trap colloidal nanoparticles from their dispersions.

However, the assemblies made by this technique until today are limited to monolayer assemblies and these assemblies generally suffer from compactness by presenting unwanted gaps of sizes larger than the size of two adjacent nanoparticles, thus seriously limiting their possible application.

The article by Shien-Derivad Tzeng et al. entitled “Templated self-assembly of colloidal nanoparticles controlled by electrostatic nanopatterning on a Si3N4 / SiO2 / Si electret” published in the journal Advanced Materials, 2006 n ° 18, p. 1147-1151, describes a monolayer assembly of positively charged gold nanoparticles with high compactness. This assembly is obtained by the action of electrophoretic forces exerted between motives of negative charges inscribed on the surface of the electret substrate and positively charged gold-charged nanoparticles. The article by Palleau E. et al .: "Quantification of the electrostatic forces involved in the directed assembly of colloidal nanoparticles by AFM nanoxerography", Nanotechnology, IOP, Bristol, GB, vol. 22 n ° 32, 19 July 2011, page 325.603, describes a method of manufacturing a nanostructure formed by colloidal nanoparticles comprising a monolayer assembly of colloidal nanoparticles fixed on an electret substrate, which has a geometric shape, freely selected and predetermined, comprising the steps consisting of : in a first stage, providing an electret substrate, constituted in an electret material and having a free reception surface, then in a second stage, inscribing an electrical surface potential on the receiving surface of the electret substrate according to a predetermined reason for electrical charges corresponding to the monolayer assembly of particles, then in a third stage, contacting the electret substrate having the reception surface inscribed by the surface potential according to the desired motive of electric charges, with a colloidal dispersion, including colloidal dispersion nanoparty colloidal cells substantially neutral and electrically polarizable by the action of an external electric field, and a means of dispersion, in the form of a liquid solvent, substantially devoid of electrical polarization action, in which the colloidal nanoparticles disperse and the nanoparticles being joined to the substrate by the action of electrophoretic forces, created from the interaction between polarizable nanoparticles and the inscribed surface potential.

A first technical problem is to have a manufacturing process for mono or multilayer directed assemblies of colloidal nanoparticles, piled up as close as possible to improve the domain of the compactness of at least the first layer from the point of view of absence of unwanted gaps. of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a particle. A second technical problem, related to the first problem, is to have a manufacturing process for binary assemblies, directed single or multilayer colloidal nanoparticles of two different types, stacked as close as possible to ensure a dominated compactness of at least the first layer from the point of view of the absence of unwanted lagoons of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a particle.

To this end, the object of the invention is a method of manufacturing a micro / nano structure formed by colloidal nanoparticles fixed on an electret substrate, which has a geometric shape, freely selected and predetermined,

which comprises the stages consisting of:

in a first stage, provide an electret substrate, constituted in an electret material and having a free reception surface, then

in a second stage, successively or parallelly inscribe a surface electric potential on the receiving surface of the electret substrate according to a predetermined motive of positive and / or negative electrical charges corresponding to the monolayer or multilayer mounting of nanoparticles, then

in a third stage, contacting the electret substrate having the reception surface inscribed by the surface potential according to the desired motive of electric charges, with a colloidal dispersion during a contact time sufficiently long and less than or equal to fifteen minutes,

in which

The colloidal dispersion comprises colloidal nanoparticles substantially neutral and electrically polarizable by the action of an external electric field, and a dispersion medium in the form of a liquid solvent or a gas, substantially devoid of the action of electrical polarization, in which the nanoparticles are dispersed colloidal, and

The absolute value of the electrical potential of the surface and the concentration of the polarizable nanoparticles are respectively greater than or equal to a first threshold of electrical surface potential and a second threshold of concentration, the first and second thresholds each depending on the nature of the medium. of dispersion and the nature of polarizable nanoparticles, so that

after the first contact time, the micro / nano structure obtained is a monolayer or multilayer micro / nano structure that has the desired geometric shape and of which at least the first layer is compact as regards the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces, created from the interaction between the polarizable nanoparticles and the potential of inscribed surface.

According to particular embodiments, the manufacturing process of a micro / nano structure formed by colloidal nanoparticles includes one or more of the following characteristics:

- the assembly of colloidal nanoparticles fixed in the electret substrate, which has a geometric shape, freely chosen and predetermined, is a multilayer assembly of which at least the first layer is compact, and

the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a third threshold of surface electric potential and a fourth concentration threshold, depending on the third and fourth thresholds, each of the nature of the dispersing medium and of the nature of polarizable nanoparticles, so that

after the contact time, the micro / nano structure obtained is the multilayer micro / nano structure that has the desired geometric shape, of which at least the first layer is compact in terms of the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between electrically neutral and polarizable nanoparticles and the potential of inscribed surface;

- the assembly of colloidal nanoparticles fixed on an electret substrate, which has a geometric shape, freely chosen and predetermined, is a multilayer assembly of a certain number Nc of layers, each of whose layers is compact as regards the absence of unwanted holes of sizes larger than the size of two adjacent nanoparticles, preferably the size of a nanoparticle, and

the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are, respectively, greater than or equal to a fifth threshold of surface electric potential and a sixth concentration threshold, each of the fifth and sixth thresholds depending on the nature of the dispersion medium, the nature of polarizable nanoparticles and the number of layers, so that

After the contact time, the micro / nano structure obtained is the multilayer micro / nano structure that has the desired geometric shape, of which all whose layers are compact in terms of the absence of unwanted holes of larger size or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the inscribed surface potential.

According to a first embodiment, the object of the invention is also a method of manufacturing a binary micro / nano structure formed by two types of nanoparticles formed by two types of colloidal nanoparticles comprising:

a first monolayer assembly of colloidal nanoparticles of the first type, fixed on an electret substrate, and having a first geometric shape, freely chosen and predetermined, and

a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, fixed on an electret substrate, and having a second geometric shape, freely chosen and predetermined, comprising the method

the stages that consist of:

in a first stage, provide an electret substrate, made of an electret material and having a free reception surface, and then

in a second stage, sequentially or in parallel, an electrical surface potential is recorded on the receiving surface of the electrolyte substrate according to a predetermined motive of electric charges having a first sign and electric charges having a second sign opposite the first , the motive of charges being composed of a first submotive of charges of the first sign, which corresponds to the first mono-layer assembly of nanoparticles of the first type, and a second submotive of charges of the second sign, which corresponds to the second monolayer or multilayer assembly of nanoparticles of the second type,

in a third stage, contacting the electret substrate having the reception surface inscribed by the surface potential, with a first colloidal dispersion during a first period of contact,

the first colloidal dispersion including nanoparticles of the first type electrically charged according to the second sign and a first dispersion means in the form of a liquid solvent or a gas, and the first contact period being long enough to allow it to form in the first submotive of charges inscribed in the electret substrate, the first monolayer assembly, which has the first desired geometric shape, of nanoparticles of the first type attached to the substrate by the action of electrophoretic forces, created from the culombian interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges, then

in a fourth stage, dry the electret substrate and the first assembly, forming together an intermediate micro / nano structure at the end of the third stage, removing the first dispersion medium and then

in a fifth stage, contact the dry intermediate structure with a second colloidal dispersion during a second contact period,

the second colloidal dispersion comprising colloidal nanoparticles of the second type, substantially neutral and electrically polarizable by the action of an external electric field, and a second dispersion means in the form of a liquid solvent or a gas, substantially devoid of electrical polarization action, in which the colloidal nanoparticles of the second type disperse, and

The absolute value of the surface electrical potential and the concentration of the nanoparticles of the second type are respectively greater than or equal to a first threshold of surface electrical potential and a second concentration threshold, each of which depends on the nature of the second medium. of dispersion and the nature of polarizable second type nanoparticles, so that

after the second contact time sufficiently long and less than 15 minutes, the second assembly obtained is the second monolayer or multilayer assembly having the second desired geometric shape and of which at least the first layer is compact in terms of absence of unwanted holes of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the surface potential of the second submotive.

According to a second embodiment, the object of the invention is also a method of manufacturing a binary micro / nano structure formed by two types of colloidal nanoparticles comprising

a first monolayer or multilayer assembly of colloidal nanoparticles of the first type, fixed on an electret substrate, and having a first geometric shape, freely chosen and predetermined, and

a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, fixed on an electret substrate, and having a second geometric shape, freely chosen and predetermined, comprising the method

the stages that consist of:

in a first stage, provide an electret substrate, consisting of an electret material and having a free reception surface, and then

in a second stage, successively or in parallel, a first surface electric potential is recorded on the receiving surface of the electret substrate according to a first predetermined submotive of electric charges having a first sign, corresponding to the first assembly of nanoparticles of the first type, the first submotive comprising a first part of a charging motif that also comprises a second predetermined submotive of electric charges having a second sign opposite the first sign,

in a third stage, contacting the electret substrate having the receiving surface inscribed by the first surface potential, with a first colloidal dispersion during a first contact period of less than or equal to 15 minutes,

the first colloidal dispersion comprising nanoparticles of the first type either electrically charged according to the second sign, or substantially neutral and electrically polarizable, and a first dispersion medium in the form of a liquid solvent or gas, the first period of contact being sufficiently long to allow it to form in the first submotive of charges inscribed in the electret substrate, the first set having the first monolayer or multilayer geometric form of nanoparticles of the first type adhered to the substrate, either by the action of electrophoretic forces, created from the culombian interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges when the nanoparticles of the first type are electrically charged according to the second sign, either by the action of dielectrophoretic forces created from the interaction between the nanoparticles polarizable and the potential of s the surface of the first submotive of charges when the nanoparticles of the first type are substantially neutral and electrically polarizable,

in a fourth stage, dry the electret substrate and the first set, forming together an intermediate micro / nano structure at the end of the third stage, and

in a fifth stage, successively or parallelly inscribe a second surface electrical potential on the receiving surface of the electret substrate of the dry intermediate structure and outside the areas covered by the first set, according to the second predetermined submotive of electrical charges having the second sign, and in a sixth stage, contact the intermediate structure inscribed by the second surface potential with a second colloidal dispersion during a second period of contact,

the second colloidal dispersion comprising electrolytically polarizable and electrically polarizable nanoparticles of the second type by the action of an external electric field, and a second dispersion means in the form of a liquid solvent or a gas, substantially devoid of electrical polarization action in which disperse colloidal nanoparticles, and

the value of the surface electric potential and the concentration of nanoparticles of the second type being respectively greater than or equal to a first threshold of surface electric potential and a second concentration threshold, each of the first and second thresholds depending on the nature of the second dispersion medium and the nature of the second type of polarizable nanoparticles, so that

After the second contact time, the second assembly obtained is the second monolayer or multilayer assembly that has the second desired geometric shape and of which at least the first layer is compact as regards the absence of larger or equal unwanted gaps. at the size of two adjacent nanoparticles of the second type, preferably the size of a nanoparticle of the second type, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the potential Superficial of the second submotive.

According to particular embodiments, the manufacturing processes of a binary micro / nano structure formed by two types of colloidal nanoparticles described above comprise one or more of the following characteristics:

- colloidal nanoparticles of the first type possess the property of converting a radiation in the near infrared spectrum (NIR) into a radiation in a first visible spectrum, and the nanoparticles of the second type have the property of converting the same radiation into the near infrared spectrum (NIR) in radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum.

- the concentration of charged nanoparticles of the first type, the first dispersion medium, the nanoparticles of the first type in terms of size, the first submotive of charges, the first contact period, the concentration of polarizable nanoparticles of the second type, the second dispersion medium, the nanoparticles of the second type in terms of size and polarization, and the second contact period are chosen to obtain the first assembly with the first geometric form and the second assembly with the second desired geometric form being the first and second geometric forms conjugate forms and having the same height with respect to the substrate receiving surface, so that the geometric form of the first set and the geometric form of the second set separated cannot be topographically detected by AFM or by optical microscopy using illumination in the visible spectrum.

According to particular embodiments, the manufacturing processes of a micro / nano structure of colloidal nanoparticles described above comprise one or more of the following characteristics:

- the stage of inscription of the surface electric potential on the receiving surface of the electret substrate according to a motive of charges is optionally carried out,

by a procedure of sequential registration of positive and / or negative charges in the electret substrate comprised in the set consisting of an inscription of electric charges by a focused ion beam, an inscription of electric charges by a focused electron beam, an inscription of electric charges by atomic force microscopy (AFM) and an inscription of electric charges by electrophotography,

by a parallel registration procedure of positive and / or negative charges on the electret substrate included in the set consisting of the electrical nano-impression and the electrical microcontact.

- The electret material is a material included in the set consisting of methyl polymethacrylates (PMMA), copolymers of cyclic olefins (CoC), polyethylene terephthalate (PET), polydimethylsiloxanes (PDMS), polypropylenes (PP), polycarbonates (PC), polystyrenes (PS), polyvinyl chloride (PVC), polytetrafluoroethylene (PFTE), triglycine sulfate (TGS), polyvinylidene fluoride (PVDF), silicon nitride. (Si3N4), silicon oxide (SO2), compound SiaN4 / SiO2 / Si (NOS);

substantially neutral and electrically polarizable colloidal nanoparticles are compounds stabilized by themselves or by ligands and / or charges, which have physical properties comprised in the set formed by the plasmonic, conductive, magnetic, luminescent, catalytic, electrochromic, photochromic properties, which are they become substantially neutral and electrically polarizable, made from basic colloidal nanoparticles,

the basic colloidal nanoparticles having a strong core and, optionally, a shell, and which are comprised in the group consisting of latex, SO2, TO2, ZrO2; CdS, CdSe, PbSe, GaAs, GaN, InP, ln2O3, ZnS, ZnO, MoS2, Si, C, ITO, Fe2O3, Fe3O4, Co, Fe-Co, Fe3C, FesC2, Ni; Au, Ag, Cu, Pt and bimetallic nanoparticles; WO3; NaLnF4, lanthanide fluorides (LnF3), lanthanide oxides (Ln2O3), zirconates, silicates, hydroxides (Ln (OH) 3) and sulfides of oxides doped or not with one or several different lanthanides (indicating Ln a lanthanide), mixtures of these compounds, and the dispersible medium of polarizable nanoparticles is optionally a liquid solvent or a non-polarizing gas,

the liquid solvent being comprised in the group consisting of pentane, iso-pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, benzene, toluene, methylcyclohexane, xylene, mesitylene, chloroform, chloride methylene, tetrachlorethylene,

the non-polarizing dispersant gas comprised in the group consisting of dinitrogen N2, argon Ar and air, and - the method of manufacturing a colloidal nanoparticle microstructure / nano-structure defined above comprises the additional steps consisting of:

choose and locate by spatial coordinates in the electret substrate where the assembly has been formed, a surface area not covered by the assembly in which the nanoparticles have been fixed by chance and uncontrolled, in the form of a structure resulting from noise deposition with a dense distribution in terms of compactness, random and dependent on the sample of the electret substrate on which the assembly has been formed, and

capturing an image of the random structure of the nanoparticles deposited in the selected surface area and forming a signature, the image being optionally captured as an AFM topographic image, an optical image or a photoluminescence image, and

save the captured image and the spatial coordinates of the corresponding surface area in a memory. A subject of the invention is also a micro / nano structure formed by colloidal nanoparticles comprising

an electret substrate consisting of an electret material and having a free receiving surface in which an electrical surface potential is inscribed on the receiving surface of the electret substrate according to a reason for positive and / or negative electrical charges,

an assembly of colloidal nanoparticles fixed in the electret substrate, with a geometric shape,

in which

colloidal nanoparticles are substantially neutral electrically polarizable by the action of an external electric field, and

The polarizable nanoparticles are arranged in monolayer or multilayer joining directly to each other and / or to the substrate by the action of dielectrophoretic forces, created by the interaction between the polarizable nanoparticles and the surface potential of the loading motif, and

the reason for electric charges of the same polarity inscribed in the electret substrate corresponds to the geometric shape of the set of monolayer or multilayer nanoparticles, and

the absolute value of the surface electric potential created by the motive of charges is greater than or equal to a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and such that at least the first layer of the colloidal nanoparticle set It is compact in terms of the absence of unwanted gaps larger than the size of two adjacent nanoparticles, preferably the size of a nanoparticle.

According to particular embodiments, the micro / nano structure formed by colloidal nanoparticles has one or more of the following characteristics:

The absolute value of the electric surface potential created by the motive of charges is greater than or equal to a third threshold that depends on the nature of the polarizable nanoparticles and in such a way that the assembly is multilayer.

The invention also aims at a micro / nano structure formed by colloidal nanoparticles of two different types comprising in the form of a binary assembly

an electret substrate consisting of an electret material and having a free reception surface,

a first monolayer or multilayer assembly of colloidal nanoparticles of the first type, fixed to the electret substrate, in which the electret substrate comprises an electrical surface potential inscribed on the receiving surface of the electret substrate according to a predetermined motive of electrical charges having a first sign and having a second sign opposite the first sign, the motive of loading of a first submotive of charges of the first sign and a second reason of loading of the second sign being composed, and

the nanoparticles of the first type that form the first set of monolayer or multilayer are charged either electrically according to the second sign and are joined to the electret substrate by the action of the coulombian forces created by the interaction between the nanoparticles of the first type and the potential of surface of the first submotive of charges inscribed in the electret substrate, either substantially neutral and electrically polarizable and joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between the nanoparticles of the first type and the surface potential of the first load submotive inscribed in the electret substrate, and

colloidal nanoparticles of the second type that form the second set of monolayer or multilayer, are substantially neutral and electrically polarizable by the action of an external electric field, are joined together and / or to the substrate by the action of dielectrophoretic forces created from of the interaction between the nanoparticles of the second type and the surface potential of the second submotive of charges inscribed in the electret substrate, and

the second submotive of electric charges of the second sign inscribed on the electret substrate corresponds to the geometric shape of the second set of monolayer or multilayer nanoparticles, and

The absolute value of the surface electric potential created by the motive of charges is greater than a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and in such a way that at least the first layer of the second set of nanoparticles Colloidal is compact in the absence of unwanted gaps of sizes larger or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle.

According to particular embodiments, the micro / nano structure formed by colloidal nanoparticles of two different types has one or more of the following characteristics:

- nanoparticles of the first type and nanoparticles of the second type respectively have a first size and a second size, and

the first and second sets respectively have a first number and a second number of layers, and the product of the first number of layers by the first size and the product of the second number of layers by the second size are substantially equal, and

the forms of the first and second voltage submotives in terms of intensity coding, sign of the potential on the receiving surface of the electret substrate are configured so that the first and second geometric shapes respectively of the first set and the second set are conjugate forms and have substantially the same height with respect to the substrate receiving surface, thus making the geometric shape of the first set and the geometric shape of the second set undetectable separately topographically by AFM and / or by optical microscopy using spectrum illumination visible; Y

- nanoparticles of the first type have the property of converting a radiation in a near-infrared (NIR) spectrum into a visible first-spectrum radiation, and nanoparticles of the second type have the property of converting the same radiation into the near-infrared spectrum ( NIR) in a radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum.

A subject of the invention is also an anti-imitation and / or traceability and / or authentication label tag comprising a micro / nano colloidal nanoparticle structure as defined above or obtained by the process as defined above.

The invention will be better understood and other advantages thereof will appear more clearly upon reading the following description of various embodiments of the invention, which are offered by way of example only and are made with reference to the accompanying drawings, in which:

- Figure 1 is a view of a method of manufacturing a micro / nano structure according to the invention; - Figure 2 is a Kelvin force microscopy (KFM) view of a series of negative and positive electrical charge lines injected into an electret substrate;

- Figures 3 and 4 are AFM and scanning electron microscopy (SEM) images of nanoparticle assemblies developed according to the loading motifs described in Figure 2 at two respective concentrations Co and Co / 40; - Figure 5 is a view of the relationship between the height of the polarizable neutral nanoparticle assemblies and the absolute value of the surface potential of the motifs of inscribed charges, for different concentrations of the same colloidal dispersion;

- Figure 6 is a topographic view of a directed assembly formed by charged nanoparticles;

- Figure 7 is a view of the correlation between the height of the polarizable neutral luminescent nanoparticle assemblies and the relative intensity of luminescence;

- Figure 8 is a set of an AFM topographic view and a luminous intensity coded view of a three-dimensional assembly of neutral and polarizable colloidal nanoparticles;

- Figure 9 is a flow chart of a process according to the invention of manufacturing a directed assembly of nanoparticles of the same type;

- Figures 10, 11, 12 are views of different phases of the realization of a binary assembly of two types of nanoparticles, respectively, the KFM image of a motif of charges composed of a first submotive and a second submotive of sign loads opposites and conjugate forms, the topographic image AFM of the development of the first submotive, and the topographic image AFM of the development of the entire motive in which the limit of the first and second submotives is undetectable;

- Figures 13, 14, 15 are the photoluminescence cartographies of the assemblies of Figure 12, respectively adapted to the optical spectrum of the two submotives, to the optical spectrum of the first submotive alone, and to the spectrum of the second submotive alone;

- Figure 16 is a flow chart of a first embodiment of manufacturing a binary assembly according to the invention;

- Figure 17 is a view of a seal, used to register in parallel and successively the charges of a first sign, then the charges of a second sign, or the charges of the same type but with different densities;

- Figure 18 is a flow chart of a second embodiment of manufacturing a binary assembly according to the invention;

- Figure 19 is an optical microscopy view of a three-dimensional QR code (in English rapid response) performed by a method of the invention.

According to Figure 1, a procedure 2 in atomic force microscopy nanoxerography AFM, which is used to assemble p-NaYF4 colloidal nanocrystals, stabilized by oleates and doped with lanthanides from their hexane dispersions, comprises a first stage 4, a second stage 6 and a third stage 8, executed successively.

In the first stage 4, the motifs 10 of electric charges are inscribed, injecting successively following the points, positive and / or negative charges on a receiving surface 12 of an electret substrate 14, here a methyl polymethacrylate (PMMA) film of 100 nanometers thick, with the help of an AFM 16 tip, polarized under ambient conditions and powered by a voltage generator 18.

The first stage 4 is executed during a writing period, usually between a few seconds and a few minutes, and depending on the complexity of the loading motifs pointed out.

In the second stage 6, the electret substrate 14, whose reception surface 12 is inscribed for the reasons 10 of electric charges, is contacted for a period of contact, in this case equal to 30 seconds, with a dispersion 20 of the colloidal nanocrystals 22, dispersed in solvent 24, in this case hexane.

The contacting shown in Figure 1 is carried out in this case by a total immersion of the electret substrate during a period of incubation in the dispersion 20.

Alternatively, the contacting is carried out by depositing a drop of the dispersing solvent on the inscribed receiving surface for reasons of electric charge during an incubation period. This variant is made with the condition that the surface of the motifs has a size compatible with the size of the solvent drop and that the solvent is not too volatile.

Alternatively, the dispersing solvent is replaced by a non-polarizing dispersing gas.

In the third stage 8, the electret substrate 14 on which the nanocrystals have been deposited in the form of linear motifs 26, is dried under ambient conditions, that is, at a pressure of approximately one atmosphere and a temperature close to 25 ° C .

According to Figure 2, a surface potential mapping 50 observed by Kelvin Force Microscopy (KFM) comprises a sequence 52 of 12 lines 54 of algebraically increasing surface potential from left to right in Figure 2, lines 54 of potential for surface are numbered from 1 to 12 going to the right of figure 2.

The first six lines 1 to 6 of surface potential correspond to the negative charges recorded and the last six lines 7 to 12 of the surface potential correspond to the positive charges recorded.

The surface potential lines 54 correspond to lines recorded during step 4 of Figure 1 by the AFM technique that uses voltage pulses ranging from -85 V to 85 V.

It should be noted that the writing stage 4 of electric charges does not change the topography of the PMMA electret film. According to Figures 3 and 4, the effects of the surface potential of the units of loading motifs and the concentration of the colloidal nanocrystals p-NaYF4: Er3 +, Yb3 + dispersed in hexane, on the morphologies of the assemblies are evaluated and represented. nanocrystals obtained by the procedure 2 of figure 1.

In Figures 3 and 4, the same surface potential mapping as described in Figure 2 has been used. In Figures 3 and 4, p-NaYF4 nanocrystals: Er3 +, Yb3 +, high conversion in green, so spherical and 22 nanometers in diameter, dispersed in hexane, are used during step 6 of Figure 1, at two respectively different concentrations, at Co equal to 7.8 * 1012 NC / ml in Figure 3, and Co / 40 = 1.9 ^ 1011 NC / ml in Figure 4. Each of Figures 3 and 4 respectively comprises an AFM 60, 62 topographic image of the corresponding directed nanocrystal assembly, an analysis of the corresponding cross-section 70, 72 and two SEM 80, 82, 90, 92 scanning electron microscopy images of the assembly of the nanoparticles in two lines of representative charges, lines numbered 8 and 11.

According to Figure 3, when loading motifs are developed using NaYF4 nanocrystals in the concentration of C0, which is high enough to consider dispersion as an infinite deposition of colloidal nanocrystals, multilayer and compact assemblies of nanoparticles in the lines of positive and negative charges, whose average height increases progressively with the absolute value of the surface potential of the motifs of charges.

According to Figure 4, when the concentration of the nanoparticle dispersion decreases by a factor of 40, that is to say C0 / 40, only monolayer assemblies of nanocrystals are formed in the lines of positive and negative charges, regardless of their potential Of surface. However, an increase in the density of nanocrystals occurs when the absolute value of the surface potential of the load lines increases.

As shown in images SEM 90, 92, these monolayer assemblies of colloidal nanocrystals form islets of colloidal nanoparticles in image 90 corresponding to a line 8 of charges that have a surface potential strictly below a certain threshold, and form a compact group of colloidal nanoparticles compressed in image 92, which corresponds to a line 11 of charges having a surface potential greater than or equal to said determined threshold.

According to Figure 5, there is a relationship of linear dependence between the average height of colloidal nanocrystal assemblies and the absolute value of the surface potential of the load lines, as well as the concentration of colloidal nanocrystals. The observed average height of colloidal nanocrystal assemblies obtained for concentrations of nanocrystals greater than or equal to C0 corresponds well to the height calculated theoretically for a compact filling of nanocrystals arranged in a cubic mesh arrangement centered on the face or a hexagonal mesh arrangement , these theoretical heights being represented by fine dotted lines 102. The height of the assemblies can be controlled and directed from a height of approximately 25 nm, corresponding to a monolayer of NaYF4 colloidal nanocrystals to a maximum height of 350 nm corresponding to fifteen layers of NaYF4 colloidal nanocrystals due to the limitation of the inscribed surface potential in this case. The minimum concentration of colloidal nanocrystals necessary to obtain the maximum height for a given load potential is 3.9 * 1012 NC / ml in this case.

It should be noted that the evolution of the average height of colloidal nanoparticle assemblies as a function of the surface potential of the load lines is substantially symmetric of the two positive and negative sides of the potential axis. In other words, the mounting height of colloidal nanoparticles depends on the absolute value of the surface potential of the load lines and does not depend on their sign. This indicates that the almost electrically neutral NaYF4 colloidal nanocrystals have been electrically polarized by the action of the electric field gradient, not uniform and created by the inscribed charging motifs, and are trapped by these motives by the action of dielectrophoretic forces only.

Figure 6 comprises a topographic image AFM 110 and a graph 112 of two cross sections, corresponding respectively to a registered motif of rectangular negative charges located in the upper half of Figure 6 and a registered motif of rectangular positive charges located in the middle part bottom of figure 6.

According to Figure 6 and in a different way from that described in Figures 1 to 5, a solution of colloidal nanocrystals p-NaYF4: E r3 +, Yb 3 + positively charged and dispersed in water at a concentration of 1.0 x 1013 NC / ml makes it possible to obtain directed monolayers of colloidal nanocrystals deposited only on the negatively charged motifs (i.e., with opposite charge to the nanocrystals), in this case a single motif 114 in Figure 6, regardless of the surface potential of the motifs loading or concentration of colloidal nanocrystals. The assembly of colloidal nanocrystals in this case is driven exclusively by culombian forces, that is, an attraction of colloidal nanocrystals in the motive of opposite charges and a repulsion of colloidal nanocrystals of the motif of the same charges. In contrast to the invention, these assemblies are never organized into compact structures of closely compacted colloidal nanoparticles, due to electrostatic repulsion forces between charged nanocrystals.

Therefore, according to the invention, the density of colloidal nanoparticles in the charge motifs varies and is regulated according to the surface potential of the charge motifs and the concentration of electrically polarizable neutral nanoparticles.

The results related to the invention, such as those described above, indicate that, in general, a substantially neutral and electrically polarizable p-NaYF4 colloidal nanocrystals assembly, directed from electrostatic forces from their dispersion to the motifs of charges, is governed by (i) the surface potential of the loading motif, (ii) the concentration of the nanocrystals in the dispersion and (iii) the polarity of the dispersion solvent.

These results are not limited to p-NaYF4 nanocrystals and can be generalized to a broader list of colloidal nanoparticles. The formation of multilayer nanoparticle assemblies is not limited to p-NaYF4 nanoparticles. For example, multilayer assemblies can also be obtained for gold nanoparticles dispersed in hexane dispersions.

Figure 7 comprises a topographic image AFM 200 of six nanocrystals assemblies of p-NaYF4 Er3 +, Yb3 + neutral and polarizable of different heights, and a graph 201 of the evolution of the intensity of the photoluminescence as a function of the height of these mounts of photoluminescent nanocrystals.

According to Figure 7, the relationship of dependence between the height of six sets 202, 204, 206, 208, 210, 212 of colloidal nanocrystals p-NaYF4 Er3 +, Yb3 + and its luminescence property is illustrated.

Assemblies 202, 204, 206, 208, 210, 212 are assemblies of colloidal nanocrystals p-NaYF4 Er3 +, Yb3 + directed on loading motifs inscribed in squares of 5pm x 5pm whose surface potentials increase from left to right in image 200 of Figure 7. Accordingly, the height of the mounts 202, 204, 206, 208, 210, 212 varies from 20 nm to 280 nm. The luminescence resulting from the high conversion of nanoparticle assemblies when excited by a continuous carrier laser diode of 980 nm wavelength corresponds to that obtained from dispersions using hexane as dispersant solvent. As shown in Figure 201 of Figure 7, the luminescence intensity of the high conversion in the visible green (corresponding to a wavelength of 525/545 nm) of colloidal nanocrystal mounts increases progressively as a function of their height . Clearly, the luminescence intensity resulting from the high conversion increases when the number of emitters, formed by the nanocrystals, increases.

The control offered by the AFM nanoxerography in the architecture of the assembly, as regards any desired geometric shape of the motif or the height and height of the assembly, makes it a suitable technique for the construction of labels against counterfeiting and / or traceability and / or authentication. The anti-counterfeit function of a label when the label is provided with said function has one or more high levels of security.

According to Figure 8, a topographic image 250 is provided by AFM microscopy and an optical luminescence image 252 of a multilayer three-dimensional assembly 254 of colloidal nanocrystals, which has the original shape of a "Smiley".

The colloidal nanocrystals of assembly 254 are p-NaYF4 colloidal nanoparticles: Er3 +, Yb3 22 nm in diameter and stabilized in oleate. The nanocrystals are deposited in a loading motif that has the form of "Smiley". In this assembly, the height of the contour and the height of the characteristic features of the face of the "Smiley" are respectively equal to 100 nm and 350 nm.

According to Fig. 8, a curve 260 of the evolution of the luminescence intensity of the assembly 254 is provided along a cut line indicated by 262 in the photoluminescence image 252, and a curve 264 of the height of the assembly at along the same corresponding cut line indicated by 266 in the topographic image AFM 250.

The relative intensities of conversion luminescence emitted from the different parts of the assembly are very well correlated with the height measured by the cross-sectional analysis of the AFM topographic image according to curve 264.

In general and according to Figure 9, a method 300 of manufacturing a micro / nano structure formed by colloidal nanoparticles comprising a monolayer or multilayer assembly of colloidal nanoparticles fixed on an electret substrate, which has a freely chosen and predetermined geometric shape, and at least the first layer of which is compact as regards the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a particle, comprises a succession of stages 302, 304, 306

In a first stage 302, an electret substrate is provided, made of an electret material and having a free reception surface.

Then, in a second stage 304, an electrical surface potential is inscribed on the receiving surface of the electret substrate according to a predetermined motive of electric charges of the same sign and / or opposite signs corresponding to the monolayer or multilayer nanoparticle assembly that is sought to be obtained. .

Then, in a third stage 306, the electret substrate, which has the receiving surface inscribed by the surface potential according to the desired motive of electric charges, is contacted with a colloidal dispersion during a contact time.

The colloidal dispersion comprises colloidal nanoparticles neutral or almost neutral electrically and electrically polarizable by the action of an external electric field, and a dispersing medium in the form of a liquid solvent or a gas that is substantially devoid of electrical polarization action, in which disperse colloidal nanoparticles.

The absolute value of the surface electric potential and the concentration of polarizable nanoparticles are, respectively, greater than or equal to a first threshold of surface electric potential and a second concentration threshold, each depending on the nature of the dispersing medium and of the nature of polarizable nanoparticles, so that after a sufficiently long contact time and less than 15 minutes, the micro / nano structure obtained is a monolayer or multilayer micro / nano structure that has the desired geometric shape and of which at least the first layer is compact in terms of the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces, created from the interaction between polar nanoparticles izables and the inscribed surface potential.

Alternatively, the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a third threshold of surface electric potential and a fourth concentration threshold, each of the third and fourth thresholds depending on the nature of the dispersing medium and the nature of the polarizable nanoparticles, so that after a sufficiently long contact time and less than fifteen minutes, the micro / nano structure obtained is the multilayer micro / nano structure having the desired geometric shape, of which at least the first layer is compact in the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between nanoparties Neutral and electrically polarizable cells and the inscribed surface potential.

Alternatively, the assembly of colloidal nanoparticles attached to an electret substrate, which has a geometric shape, freely selected and predetermined, is a multilayer assembly of a number Nc of layers, each of whose layers is compact as regards the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle.

The electrical surface potential and the concentration of polarizable nanoparticles are, respectively, greater than or equal to a fifth threshold of surface electrical potential and a sixth concentration threshold, each of the fifth and sixth thresholds depending on the nature of the dispersing medium, of the nature of polarizable nanoparticles and the number of layers, so that after a contact time long enough and less than 15 minutes, the micro / nano structure obtained is the multilayer micro / nano structure that has the desired geometric shape , of which the layers are compact, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the inscribed surface potential.

Colloidal nanoparticles have physical properties comprised in the set consisting of plasmonic, conductive, magnetic, luminescent, catalytic, electrochromic and photochromic properties.

For example, each of the colloidal nanoparticles carries a lanthanide capable of converting radiation in a near infrared (NIR) spectrum into radiation in a visible spectrum.

Alternatively, the step of registering the motives of charges on the receiving surface of the electret substrate can optionally be carried out by means of a successive inscription procedure of the electric charges on the electret substrate, or a parallel inscription procedure of electric charges on the substrate electret

A sequential inscription procedure is included in the set consisting of an inscription of electric charges by a beam of focused ions, an inscription of electric charges by a beam of focused electrons, an inscription of electric charges by atomic force microscopy (AFM) and an inscription of electric charges by electrophotography (also called xerography).

It should be noted that the inscription of electric charges by atomic force microscopy (AFM) allows advantageously to inscribe in a single uninterrupted stage or in a single step a charge motive comprising both positive and negative charges.

A parallel enrollment procedure is included in the set consisting of the electric nano-print and the electric micro-contact.

Alternatively, an area of the sample surface of the electret substrate on which the assembly on the receiving surface of the electret substrate outside the assembly is formed is chosen. In this selected surface area, at the moment when the solution comes into contact with the substrate loaded with the nanoparticles in a reduced amount, they are fixed in an accidental and uncontrolled manner, in the form of a structure resulting from a deposition noise. which has a little dense distribution in terms of compactness, random and dependent on the sample of the electret substrate on which the assembly has been formed. In a first monitoring stage, the surface area is followed by spatial coordinates in a frame attached to the electret substrate. In a second stage, an image of the random structure of the nanoparticles fixed in the area of the selected surface and forming a signature is captured. The captured image is optionally an AFM topographic image, an optical microscopy image or a photoluminescence image. The captured image and spatial coordinates of the selected surface area are stored in a storage memory. or a photoluminescence image. The captured image and spatial coordinates of the selected surface area are stored in a storage memory.

In general, the electret material is a material in the group consisting of methyl poly-methacrylates (PMMA), cyclic olefin copolymers (CoC), polyethylene terephthalate (PET), polydimethylsiloxanes (PDMS), polypropylenes (PP), polycarbonates (PC), polystyrenes (PS), polyvinyl chlorides (PVC), polytetrafluoroethylenes (PFTE), triglycine sulfate (TGS), polyvinylidene fluoride (PVDF), silicon nitride (Si3N4), silicon oxide (SiO2), compound Si3N4 / SiO2 / Si (n Os).

In general, colloidal nanoparticles are compounds stabilized by themselves or by ligands and / or charges, which have physical properties comprised in the set consisting of plasmonic, conductive, magnetic, luminescent, catalytic, electrochromic, photochromic properties that have become substantially neutral and electrically polarizable, made from basic colloidal nanoparticles.

The basic colloidal nanoparticles have a solid core and, eventually, a shell, and are included in the group consisting of latex, SiO2, TiO2, ZrO2; CdS, CdSe, PbSe, GaAs, GaN, InP, In2O3, ZnS, ZnO, MoS2, Si, C, ITO, Fe2O3, Fe3O4, Co, Fe-Co, Fe3C, FesC2, Ni; Au, Ag, Cu, Pt and bimetallic nanoparticles; WO3; NaLnF4, lanthanide fluorides (LnF3), lanthanide oxides (Ln2O3), zirconates, silicates, hydroxides (Ln (OH) 3) and sulfides of oxides doped or not with one or several different lanthanides (indicating Ln a lanthanide), mixtures of these compounds. When the dispersing medium is a non-polarizing liquid solvent, the solvent is comprised of the group consisting of pentane, isopentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, benzene, toluene, methylcyclohexane, xylene, mesitylene, chloroform, methylene chloride, tetrachlorethylene.

When the dispersing medium is a non-polarizing dispersing gas, the dispersing gas is included in the group consisting of dinitrogen N2, argon Ar and air.

According to Figures 10, 11 and 12, the inscription of charges by AFM can also be used to make binary colloidal nanoparticle assemblies with precisely directed and controlled placement of two types of colloidal nanoparticles. This type of binary assembly offers a high degree of safety for traceability and anti-counterfeiting marks.

According to Figures 10, 11 and 12, a binary assembly 402 has been manufactured using a motif of charges 404 comprising both positive and negative charges, and dispersions of nanoparticles based on p-NaYF4, different by their electrical charges, their degrees of polarizability, its concentrations and its high conversion emission bands. The binary assembly 402 manufactured thus allows to obtain a color-coded micro motif.

According to Figure 10, an image KFM 405 of the surface potential of the micromotive 404 is provided, which is used to create the binary assembly 402.

The micromotive of charges 404 used to create the binary assembly consists of a mark 406, in the form of a question mark negatively charged 1.5 pm wide, in contrast to a square bottom 408 positively charged 15 pm sideways. The micromotive 404 has been developed using successively two different dispersions of colloidal nanocrystals (i) a first dispersion of a first type of nanoparticles, core / shell nanocrystals p-NaYF4: Gd3 +, E r3 +, Yb3 + / NaYF4, high conversion to green light , positively charged and dispersed in water, and (ii) a second dispersion of a second type of nanoparticles, core / shell nanocrystals of p-NaYF4: Gd3 +, Tm3 +, Yb3 + / NaYF4, high conversion to blue light, almost electrically neutral and dispersed in hexane. The two types of nanocrystals have similar sizes here and both types of colloidal nanoparticles can be optically pumped by the same source of optical excitation due to the fact that both types of nanoparticles contain Yb3 + as an energy transfer agent.

According to Figure 11, a topographic image AFM 412 of the loading motif first developed in a first phase 414 using the first aqueous dispersion shows the positively charged first type nanoparticles selectively deposited according to a monolayer in the mark of the question mark 406 loaded negatively as a reason for charging.

After drying with nitrogen and removing traces of solvent from the first dispersion, the loading motif is developed in a second stage using the second dispersion having hexane as solvent. During this second stage of development, the nanoparticles of the second type, that is, the high conversion nanoparticles in blue light, are selectively deposited in a monolayer, at the bottom 408, positively charged with the electrolyte substrate and forming a part of the motif of loads. This selectivity stems from the fact that the surface potential of motif 406 corresponding to the question mark coated on the monolayer of nanoparticles of the first type is insufficient to allow a second deposition and a fixation of nanoparticles of the second type, which have a concentration adapted to this effect.

It should be noted that the positive surface potential of the bottom with positive charge has been finely regulated for writing AFM charges to obtain a density of colloidal nanoparticles of the second type, similar or identical to that of the first type nanoparticles deposited and fixed by forces of Coulomb in the mark of the question mark. Therefore, the mark of the question mark cannot be topographically perceived and distinguished from the background under an optical microscope.

According to Figure 12, the analysis of the topographic image 416 by AFM of the final assembly 402 does not allow to detect the limits of the mark of the question mark with respect to the background. Therefore, the information encoded in motif 402 is effectively hidden or merged in the background.

This encoded information can be found later through luminescence images.

According to Figure 13, when the developed mark 430 of the question mark in the visible spectrum without filtering is observed being excited by a near infrared diode laser NIR (in English Near Infrarred Radiation) of 980 nm wavelength, the 430 developed brand appears brighter than the 432 developed background, due to higher high conversion performance for p-NaYF4 nanocrystals: Gd3 +, Er3 +, Yb3 + / NaYF4, of the first type (two photon processes) than high performance conversion for the nanocrystals p-NaYF4: Gd3 +, Tm3 +, Yb3 + / NaYF4, of the second type (three photon process).

According to Figures 14 and 15, the two types of nanocrystal emissions can be effectively separated using appropriate visible filters to reveal the colors encoded in the binary assembly motif, respectively a selective blue filter (corresponding to a wavelength of 485 nm) and a selective green filter (corresponding to a wavelength of 550 nm).

In general and according to a first embodiment of Figure 16, a method 502 of manufacturing a binary micro / nano structure, formed by two types of colloidal nanoparticles, comprises a set of steps 504, 506, 508, 510 and 512, executed successively .

The binary micro / nano structure formed by two types of colloidal nanoparticles comprises a first monolayer assembly of colloidal nanoparticles of the first type, fixed on an electret substrate, and having a first geometric shape, freely chosen and predetermined, and a second monolayer assembly or multilayer of colloidal nanoparticles of the second type, fixed on an electret substrate and having a second geometric shape, chosen and predetermined freely, and of which at least the first layer is compact as regards the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles.

In a first step 504, an electret substrate is provided, formed in an electret material and having a free reception surface.

Then, in a second stage 506, a surface electric potential has been successively or parallel inscribed on the receiving surface of the electret substrate according to a predetermined motive of electric charges having a first sign and electric charges having a second sign opposite the first . The loading motif consists of a first submotive of charges of the first sign corresponding to the first monolayer assembly of nanoparticles of the first type, and a second submotive of charges of the second sign corresponding to the second monolayer or multilayer assembly of nanoparticles of the second type.

Then, in a third step 508, the electret substrate, which has the receiving surface inscribed by the surface potential, is brought into contact with a first colloidal dispersion during a first contact time.

The first colloidal dispersion comprises electrically charged nanoparticles of the first type according to the second sign and a first dispersing medium in the form of a liquid solvent or a gas.

The first contact time is long enough to allow the first monolayer of charges inscribed in the electret substrate to form the first monolayer assembly of nanoparticles of the first type attached to the substrate by the action of electrophoretic forces, created from the culombian interaction between the first type nanoparticles and the surface potential of the first submotive of charges, until the first desired geometric shape of the first assembly is obtained.

Then, in a fourth stage 510, the electret substrate and the first assembly, which together form an intermediate microstructure at the end of the third stage, are dried by removing the first solvent.

Then, in a fifth step 512, the dry intermediate structure is contacted in a second colloidal dispersion during a second contact time.

The second colloidal dispersion comprises colloidal nanoparticles of the second type, electrically neutral or almost neutral, electrically polarizable by the action of an external electric field, and a second dispersion medium, in the form of a liquid solvent or a gas, substantially devoid of action of electrical polarization, in which the colloidal nanoparticles of the second type are dispersed.

The absolute value of the surface electric potential and the concentration of nano-particles of the second type are respectively greater than or equal to a first threshold of surface electric potential and a second concentration threshold, the first and second thresholds depending on the nature of the second solvent and of the nature of polarizable nanoparticles of the second type, so that after the second contact time sufficiently long and less than about 15 minutes, the second assembly obtained is the second monolayer or multilayer assembly having the desired second geometric shape and of which at least the first layer is compact in the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from of the interaction between polarizable nanoparticles and the potential for super fiction of the second submotive.

When a sequential inscription procedure of electric charges of different polarities is carried out on the electret substrate during the second stage, it is included in the assembly formed by an inscription of electric charges by a focused ion beam, an inscription of electric charges by a beam of focused electrons, an inscription of electric charges by atomic force microscopy (AFM) and an inscription of electric charges by electrophotography (also called xerography).

When the parallel inscription procedure of charges of different polarities in the electret substrate is executed during the second stage, the electrical microcontact is included in the assembly formed by the electrical nanoimpression.

In all cases, it is possible to perform two successive injections with different electrical polarizations.

It should be noted that the sequential inscription by AFM nanoxerography allows advantageously to register in a single uninterrupted stage or in a single step a motive of charges that includes both positive and negative charges.

Alternatively, it is possible to perform a parallel registration by electric microcontact using a single seal. In this case, a two-level flexible seal is used, such as a seal 530 of elastomeric material, is represented in Figure 17. The elastomer seal 530 comprises two levels of motifs 532, 534, a first 532 and a second 534, whose first and second associated surfaces 542, 544 are conductive and electrically connected to each other to form equipotential surfaces. The first and second associated surfaces 542, 544 correspond respectively to the first submotive and the second submotive of charges.

The first and second surfaces 542, 542 are configured to be equipotential surfaces either by metallizing the entire lower surface of the seal, the flanks of joints of the first and second surfaces 542, 542 inclusive, or by using a conductive volume seal.

When a parallel inscription of different and opposite charges is made, the seal is first applied to the electret with a first force F1 sufficient to crush the second level 534 of the elastomer seal, and the first surface 542 is brought into contact at the same time. and the second surface 544 in the electret, and an injection of charges with a voltage V1 is performed.

Then, when released, the seal is applied to the electret with a second force F2 of less intensity so that only the second level of the elastomer seal, that is, only the second surface 544 is in contact with the electret and an injection of charges is carry out with a second voltage V2 of opposite polarity to that of the first voltage V1 for a time sufficient to cancel the loads registered under the voltage V1 and then register the loads of the second reason.

In general and according to a second embodiment of Figure 18, a method 602 of manufacturing a binary micro / nano structure, formed by two types of colloidal nanoparticles, comprises a set of steps 604, 606, 608, 610, 612, 614, executed successively.

In a first step 604, an electret substrate is provided, consisting of an electret material and having a flat free reception surface.

Then, in a second stage 606, a first surface electrical potential is successively or parallelly inscribed on the receiving surface of the electret substrate according to a first predetermined submotive of electric charges having a first sign, corresponding to a first set of monolayer or multilayer of nanoparticles of the first type, the first submotive comprising a first part of a charge motif that also includes a second predetermined submotive of electric charges having a second sign opposite the first sign.

Then, in a third step 608, the electret substrate, which has the receiving surface inscribed by the first surface potential, is brought into contact with a first colloidal dispersion during a first contact time.

The first colloidal dispersion contains nanoparticles of the first type either electrically charged according to the second sign, or substantially neutral and electrically polarizable, and a first dispersing medium in the form of a liquid solvent or a gas.

The first contact time is long enough to allow the first monolayer assembly of nanoparticles of the first type with the first desired geometric shape to form in the first submotive of charges inscribed on the electret substrate. The nanoparticles of the first set are bound to the substrate by the action of electrophoretic forces, created from the culombian interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges when the nanoparticles of the first type are electrically charged according to the second sign, either by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the surface potential of the first submotive of charges, until the first desired geometric shape of the first set is obtained.

Then, in a fourth stage 610, the electret substrate and the first assembly, together forming an intermediate micro / nano structure at the end of the third stage, are dried.

In a fifth step 612 below, a second surface electrical potential is inscribed successively or in parallel on the receiving surface of the electret substrate of the dry intermediate structure and outside the areas covered by the first assembly, according to the second predetermined submotive of charges electrical that have the second sign.

Then, in a sixth step 614, the intermediate structure inscribed by the second surface potential is contacted in a second colloidal dispersion during a second contact time.

The second colloidal dispersion contains colloidal nanoparticles of the second type, neutral or almost neutral, and electrically polarizable by the action of an external electric field, and a second dispersion medium in the form of a liquid solvent or a gas, substantially free of the action of electrical polarization in which colloidal nanoparticles are dispersed.

The absolute value of the surface electric potential and the concentration in nanoparticles of the second type are respectively greater than or equal to a first threshold of surface electric potential and a second concentration threshold, each of which depends on the nature of the second medium of dispersion and of the nature of the polarizable second type nanoparticles, so that after the second contact time sufficiently long and less than 15 minutes, the second assembly obtained is the second monolayer or multilayer assembly having the desired second geometric shape and the which at least the first layer is compact in terms of the absence of unwanted gaps larger than the size of two adjacent nanoparticles, the nanoparticles are joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the surface potential of the s second submotive.

The procedure of sequential registration of electric charges of the same sign on the electret substrate, executed during the second stage 606 or the fifth stage 612, is included in the set consisting of an inscription of electric charges by a beam of focused ions, an inscription of electric charges by a beam of focused electrons and an inscription of electric charges by atomic force microscopy (AFM) and an inscription of electric charges by electrophotography (also called xerography).

The process of parallel registration of charges of the same sign on the electret substrate is included in the set consisting of the electric nano-print, the electric microcontact.

In particular, colloidal nanoparticles of the first type have the property of converting a radiation in a near infrared spectrum (NIR) into a radiation in a first visible spectrum, and nanoparticles of the second type have the property of converting a radiation into the infrared spectrum near (NIR) in a radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum.

In particular, the concentration of charged nanoparticles of the first type, the first solvent, the nanoparticles of the first type in terms of size, the first loading submotive, the first contact time, the concentration of polarizable nanoparticles of the second type, the second solvent, the nanoparticles of second type in terms of size and polarizability, and the second contact time is chosen to obtain the first monolayer assembly having the first geometric shape and the second assembly having the desired second geometric shape, the first and second being geometric forms conjugate forms and having the same height with respect to the substrate receiving surface, so that the geometric shape of the second set is undetectable by AFM microscopy or by optical microscopy using illumination in the visible spectrum.

In general, and independently of the procedure carried out to perform it, a microstructure formed by colloidal nanoparticles comprises an electret substrate and a colloidal nanoparticle assembly.

The electret substrate, consisting of an electret material and with a free reception surface, is inscribed on its reception surface by an electrical surface potential according to a predetermined motive of positive and / or negative electrical charges.

The assembly of colloidal nanoparticles fixed in the electret substrate has a geometric shape, freely chosen and predetermined.

Colloidal nanoparticles are electrically neutral or almost neutral, and electrically polarizable by the action of an external electric field.

The polarizable colloidal nanoparticles are arranged in monolayer or in multilayers being directly linked to each other and / or to the substrate by the action of dielectrophoretic forces, created by the interaction between the polarizable nanoparticles and the surface potential of the loading motif.

The reason for electric charges of the same sign inscribed on the electret substrate corresponds to the geometric shape of the set of monolayer or multilayer nanoparticles.

The absolute value of the surface electric potential created by the motive of charges is greater than or equal to a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and such that at least the first layer of the colloidal nanoparticle assembly It is compact in terms of the absence of unwanted gaps greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle.

Alternatively, the absolute value of the surface electric potential created by the motive of charges is greater than or equal to a third threshold that depends on the nature of the polarizable nanoparticles, and in such a way that the assembly of colloidal nanoparticles is multilayer.

Alternatively, the microstructure is formed by colloidal nanoparticles of two different types and comprises, in the form of a binary assembly, an electret substrate, a first monolayer or multilayer assembly of colloidal nanoparticles of the first type, and a second monolayer or multilayer assembly of colloidal nanoparticles of the second type.

The electret substrate is constituted by an electret material and has a free reception surface.

The colloidal nanoparticles of the first type that form the first assembly are deposited on the electret substrate. Colloidal nanoparticles of the second type that form the second assembly are deposited on the electret substrate.

The electret substrate has a surface electric potential inscribed on the receiving surface of the electret substrate according to a predetermined motive of electric charges that have a first sign and that have a second sign opposite to the first, the motive of charges being composed of a first submotive of charges of the first sign and a second submotive of charges of the second opposite sign.

The nanoparticles of the first type that form the first monolayer assembly are electrically charged according to the second sign and are joined to the electret substrate by the action of the culombian forces created by the interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges inscribed in the electret substrate, either substantially neutral and electrically polarizable and joined to the electret substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the surface potential of the first submotive of charges.

The colloidal nanoparticles of the second type that form the second monolayer or multilayer assembly, are neutral or almost neutral electrically and polarizable and electrically by the action of an external electric field.

The colloidal nanoparticles of the second type are linked to each other and / or to the substrate by the action of dielectophoretic forces, created from the interaction between the nanoparticles of the second type, electrically neutral and polarizable, and the surface potential of the second submotive of loads registered in the electret substrate.

The second submotive of the second sign electrical charges, inscribed on the electret substrate, corresponds to the geometric shape of the second, single-layer or multi-layer, nanoparticle assembly.

The absolute value of the surface electric potential created by the second submotive of charges is greater than or equal to a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and so that at least the first layer of the second assembly Colloidal nanoparticles are compact in terms of the absence of unwanted holes of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a particle.

Alternatively, charged nanoparticles of the first type and polarizable neutral nanoparticles of the second type respectively have a first size and a second size.

The first assembly and the second assembly respectively have a first number and a second number of layers, and the product of the first number of layers by the first size is substantially equal to the product of the second number of layers by the second size.

The forms of the first and second voltage submotives as regards the intensity and sign coding of the potential on the receiving surface of the electret substrate are configured so that the first and second geometric shapes respectively of the first and second mounts are forms conjugated to each other and have substantially the same height with respect to the receiving surface of the electret substrate, which makes the geometric shape of the second set undetectable by AFM or by optical microscopy using illumination in the visible spectrum.

Alternatively, nanoparticles of the first type have the property of converting a radiation in the near infrared spectrum (NIR) into a radiation in a first visible spectrum, and nanoparticles of the second type have the property of converting radiation into the near infrared spectrum ( NIR) in a radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum.

In general, the electret material is a material comprised in the group consisting of methyl polymethacrylates (PMMA), copolymers of cyclic olefins (CoC), poly (ethylene terephthalate) (PET), polydimethylsiloxanes (PDMS), polypropylenes (PP), polycarbonates (PC), polystyrenes (PS), polyvinyl chlorides (PVC), polytetrafluoroethylenes (PFTE), triglycerine sulfate (TGS), polyvinylidene fluoride (PVDF), silicon nitride (Si3N4), silicon oxide (SiO2), the compound YES3N4 / So / yes (NOS).

In general, colloidal nanoparticles are compounds stabilized by themselves or by ligands and / or charges, which have physical properties comprised in the set formed by the plasmonic, conductive, magnetic, luminescent, catalytic, electrochromic, photochromic properties that become substantially neutral and electrically polarizable, made of basic colloidal nanoparticles.

The basic colloidal nanoparticles have a solid core and, eventually, a shell, and are included in the group consisting of latex, SiO2, TiO2, ZrO2; CdS, CdSe, PbSe, GaAs, GaN, InP, In2O3, ZnS, ZnO, MoS2, Si, C, ITO, Fe2O3, Fe3O4, Co, Fe-Co, Fe3C, FesC2, Ni; Au, Ag, Cu, Pt and bimetallic nanoparticles; WO3; NaLnF4, lanthanide fluorides (LnF3), lanthanide oxides (Ln2O3), zirconates, silicates, hydroxides (Ln (OH) 3) and oxide sulfides doped or not with one or more different lanthanides (Ln indicates a lanthanide) and mixtures of these compounds. When the dispersing medium is a non-polarizing liquid solvent, the solvent is composed of pentane, iso-pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, benzene, toluene, methylcyclohexane, xylene, mesitylene, chloroform, methylene chloride, tetrachlorethylene.

When the dispersing medium is a non-polarizing dispersing gas, the dispersing gas is comprised in the assembly formed by dinitrogen N2, argon Ar and air.

In particular, the microstructures of colloidal nanoparticles are compact single-layer and multi-layer p-NaYF4 high-conversion nano-crystal assemblies, tightened to the maximum, fixed on electret films in PMMA and 100 nm thick. The number of layers of deposited nanocrystals is precisely adjusted by the surface potential of the loading motifs inscribed in the electret films in PMM ^a and the concentration in nanocrystals in the dispersion.

The formation of multilayer nanocrystal assemblies requires motifs of loads with high surface potential, high concentrations of nanocrystals and an electrically non-polarizing dispersion solvent. The nanocrystals must be electrically polarizable to a high degree and neutral from the electrostatic point of view. Binary sets of nanocrystals are created using an electret substrate in which motifs of positive and negative charges have been inscribed and submerging in them the substrate inscribed in dispersions of nanocrystals, for example, p-NaYF4, of different electrical charges and luminescence in high Conversion of different spectra. The high conversion luminescence properties of nanocrystal mounts are well correlated with their geometry and composition.

All these characteristics allow the manufacture of micro / nanomotives of encoded nanocrystals in terms of (i) geometry, (ii) type of nanocrystals, (iii) intensity of luminescence, (iv) emission color by the use of two types of high conversion nanocrystals.

In addition, color-coded mounts can be made imperceptible in topography, thus effectively hiding information.

The speed and economic efficiency of the processes described above, the ability to write any desired geometric pattern and the control of the spatial architecture of the assembly in the three directions, designated for example by the X, Y and Z axes allow Build unique micro / nano structures of complex shapes, encoded in terms of colors and intensities, which can be used as labels against counterfeiting and / or traceability and / or authentication with a high level of security.

Labels against counterfeiting and / or traceability and / or authentication may have various levels of security, such security levels may or may not be cumulative. These security levels can be:

- the micro / nano size of the structures, which makes "invisible" to the naked eye and impossible to find with a microscope if its exact position is unknown;

- the luminescence, knowing that in the presence of binary assemblies or more than two types of nanoparticles, the micro / nano structure can have at least two different emission wavelengths;

- the luminescence intensity, the latter being able to present variations for the same micro / nano structure, these variations being due to different mounting heights within the same micro / nano structure;

- the random deposition of nanoparticles in an area of the surface of the electret substrate, excluding assembly, this deposition presenting a specific unique signature for each micro / nano structure;

- the masking of a nanoparticle assembly by one or several other nanoparticle assemblies, obtaining masking with binary assemblies or assemblies of more than two types of imperceptible nanoparticles in terms of topography, thus hiding the information effectively. Such masking makes the identification of the information topographically impossible, allowing only a luminescence reading to reveal the information.

The anti-counterfeiting and / or traceability and / or authentication tags, which have one or more security levels, also encode the information topographically, the micro / nano structure that has a specific geometry.

According to Figure 19, an anti-counterfeit and / or traceability and / or authentication tag is, for example, a three-dimensional QR code detectable in fluorescence by optical microscopy. Colloidal nanoparticles are here latex particles of 100 nm in diameter.

Alternatively, the second embodiment of method 602 described in Figure 18 can be generalized by performing a sequence in a predetermined order of an integer, greater than or equal to two, of pairs of stages, each pair of stages being associated with a sequence order or rank k in the sequence, to a predetermined type of nanoparticles, substantially neutral and polarizable to deposit dependent on the range k, and a predetermined deposition geometry dependent on the range k.

Each pair of stages, characterized by its rank k, is the succession of a first stage of inscription of rank k of a motive of charges that depends on the predetermined type of particles to deposit and the associated deposition geometry gives the function of rank k and of a second stage of deposition of nanoparticles having the type associated with the range k in the motive of charges recorded during the first stage associated with the range k.

Therefore, three-dimensional ternary sets of nanoparticles with high compactness, and assemblies with an even larger number of different types of nanoparticles can be obtained especially.

Alternatively, an anti-counterfeit and / or traceability and / or authentication tag comprising a micro / nano colloidal nanoparticle structure as defined above or obtained by the procedure defined above, further comprises:

- a structure of nanoparticles fixed in a random and uncontrolled manner according to a deposition noise, with a dense distribution in terms of compactness and randomization, made in a surface area of the electret substrate not covered by the assembly, and identified in the substrate electret by spatial coordinates, and

- an image of said random structure of nanoparticles deposited in the reference surface area, the image being optionally captured as an AFM topographic image, an optical image or a photoluminescence image, and stored in a memory.

The coordinates of the image of said random structure are stored in an information medium corresponding to the image of said random structure. The information medium is, for example, the same recording medium as that of the image. It can also be a different recording medium. In all cases, there is an informative assignment link, for example, computer, between the image of the random structure and its spatial coordinates.

Claims (18)

1. Method of manufacturing a micro / nano structure formed by colloidal nanoparticles comprising a monolayer or multilayer assembly of colloidal nanoparticles fixed on an electret substrate, which has a geometric shape, freely chosen and predetermined, comprising the steps consisting of: a first stage (302), providing an electret substrate, made of an electret material and having a free reception surface, then a second stage (4; 304), inscribing an electrical surface potential on the receiving surface of the electret substrate according to a predetermined motive of positive and / or negative electrical charges corresponding to the monolayer or multilayer mounting of nanoparticles, then in a third stage (6; 306), contacting the electret substrate having the receiving surface inscribed by the surface potential according to the desired motive of electric charges, with a colloidal dispersion for a sufficiently long and lower contact time or equal to fifteen minutes, wherein the colloidal dispersion contains colloidal nanoparticles substantially neutral or almost neutral and electrically polarizable, by the action of an external electric field, and a dispersion medium, in the form of a liquid solvent or a gas, substantially devoid of polarization action electrical, in which colloidal nanoparticles are dispersed, characterized in that the absolute value of the surface electric potential and the concentration in polarizable nanoparticles are respectively greater than or equal to a first threshold of surface electric potential and a second concentration threshold, the first and second thresholds depending on the nature of the dispersion medium and the nature of polarizable nanoparticles, so that After the first contact time, the micro / nano structure obtained is a monolayer or multilayer micro / nano structure that has the desired geometric shape and of which at least the first layer is compact in terms of the absence of unwanted gaps. of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces, created from the interaction between polarizable nanoparticles and the potential of inscribed surface. 2. Method of manufacturing a micro / nano colloidal nanoparticle structure according to claim 1, wherein: the assembly of colloidal nanoparticles fixed in the electret substrate, which has a geometric shape, freely chosen and predetermined, is a multilayer assembly of which at least the first layer is compact, and the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a third threshold of surface electric potential and a fourth threshold of concentration, the third and fourth thresholds depending on the nature of the dispersing medium and the nature of polarizable nanoparticles, so that after the contact time, the micro / nano structure obtained is the multilayer micro / nano structure that has the desired geometric shape, of which at least the first layer is compact in terms of the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between neutral and electrically polarizable nanoparticles and the inscribed surface potential. 3. Method of manufacturing a micro / nano colloidal nanoparticle structure according to claim 1, wherein: The assembly of colloidal nanoparticles fixed on an electret substrate, which has a geometric shape, freely chosen and predetermined, is a multilayer assembly of a certain number Nc each of whose layers is compact in terms of the absence of unwanted gaps of sizes larger than the size of two adjacent nanoparticles, preferably the size of a nanoparticle, and The absolute value of the surface electric potential and the concentration in polarizable nanoparticles are, respectively, greater than or equal to a fifth threshold of surface electric potential and at a sixth concentration threshold, each of the fifth and sixth thresholds of nature depending of the dispersion medium, of the nature of the polarizable nanoparticles and d the number of layers, so that After the contact time, the micro / nano structure obtained is the multilayer micro / nano structure that has the desired geometric shape, all whose layers are compact in terms of the absence of unwanted gaps of size greater than or equal to size two adjacent nanoparticles, preferably the size of a nanoparticle, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the inscribed surface potential. 4. - Method of manufacturing a micro / nano binary structure formed by two types of colloidal nanoparticles comprising: a first monolayer assembly of colloidal nanoparticles of the first type, fixed on an electret substrate, and having a first geometric shape, freely chosen and predetermined, and a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, fixed on an electret substrate, and having a second geometric shape, freely chosen and predetermined, and the process comprising the steps consisting of: in a first stage (504), provide an electret substrate, consisting of an electret material and having a free reception surface, then in a second stage (506), successively or parallelly inscribe a surface electric potential on the receiving surface of the electret substrate according to a predetermined motive of electric charges having a first sign and electric charges having a second sign opposite the first , the motive being composed of charges of a first submotive of charges of the first sign, which corresponds to the first monolayer assembly of nanoparticles of the first type, and of a second submotive of charges of the second sign, which corresponds to the second monolayer or multilayer assembly of nanoparticles of the second type, in a third stage (508), contacting the electret substrate having the receiving surface inscribed by the surface potential, with a first colloidal dispersion during a first contact time, the first colloidal dispersion containing nanoparticles of the first type electrically charged according to the second sign and a first dispersion means in the form of a liquid solvent or a gas, and the first contact time being long enough to allow it to form in the first submotive of charges inscribed in the electret substrate the first monolayer assembly, which has the first desired geometric shape, of nanoparticles of the first type attached to the substrate by the action of electrophoretic forces, created from the culombian interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges, then in a fourth stage (510), to dry the electret substrate and the first set, forming together an intermediate micro / nano structure at the end of the third stage, eliminating the first dispersion medium and then in a fifth stage (512), contacting the dry intermediate structure with a second colloidal dispersion during a second contact time, the second colloidal dispersion containing colloidal nanoparticles of the second type, substantially neutral and electrically polarizable by the action of an external electric field, and a second dispersion means in the form of a liquid solvent or a gas, substantially devoid of electrical polarization action , in which the colloidal nanoparticles of the second type disperse, and the absolute value of the surface electric potential and the concentration in nanoparticles of the second type respectively being greater than or equal to a first threshold of surface electric potential and a second concentration threshold, the first and second thresholds depending on the nature of the second medium of dispersion and the nature of polarizable nanoparticles of the second type, so that after the second contact time sufficiently long and less than 15 minutes, the second assembly obtained is the second monolayer or multilayer assembly having the desired second geometric shape and of which at least the first layer is compact in terms of absence of unwanted gaps of size greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle, are nanoparticles joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the surface potential of the second submotive. 5. Method of manufacturing a micro / nano binary structure formed by two types of colloidal nanoparticles comprising: a first monolayer or multilayer assembly of colloidal nanoparticles of the first type, fixed on an electret substrate, and having a first geometric shape, freely chosen and predetermined, and a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, fixed on an electret substrate, and having a second geometric shape, freely chosen and predetermined, the procedure comprising the following steps: in a first stage (604), provide an electret substrate, consisting of an electret material and having a free reception surface, then in a second stage (606), successively or parallelly inscribe a first surface electric potential on the receiving surface of the electret substrate according to a first predetermined submotive of electric charges having a first sign, corresponding to the first set of nanoparticles of the first type , the first submotive comprising a first part of a charging motive that also has a second predetermined submotive of electric charges having a second sign opposite the first sign, in a third stage (608), contacting the electret substrate having the receiving surface inscribed by the first surface potential with a first colloidal dispersion during a first contact period of less than or equal to 15 minutes, the first colloidal dispersion containing nanoparticles of the first type either electrically charged according to the second sign, or substantially neutral and electrically polarizable, and a first dispersion medium in the form of a liquid solvent or a gas, and the first contact time being long enough to allow the first submotive of charges inscribed in the electret substrate to form, the first set having the first monolayer or multilayer geometric form of nanoparticles of the first type attached to the substrate, either by the action of electrophoretic forces, created from the culombian interaction between the nanoparticles of the first type and the surface potential of the first submotive of charges when the nanoparticles of the first type are electrically charged according to the second sign, or by the action of dielectrophoretic forces created from the interaction between polarizable nanoparticles and the potential to surface of the first submotive of charges when nanoparticles of the first type are substantially neutral and electrically polarizable, in a fourth stage (610), dry the electret substrate and the first set, forming together an intermediate micro / nano structure at the end of the third stage (608), then in a fifth stage (612), successively or parallelly inscribe a second surface electric potential on the receiving surface of the electret substrate of the dry intermediate structure and outside the areas covered by the first set, according to the second predetermined submotive of charges electric that have the second sign, then in a sixth stage (614), contacting the intermediate structure inscribed by the second surface potential with a second colloidal dispersion during a second contact time, the second colloidal dispersion containing colloidal nanoparticles of the second type, neutral or almost neutral electrically and electrically polarizable by the action of an external electric field, and a second dispersion means, in the form of a liquid solvent or a gas, substantially devoid of electrical polarization action in which colloidal nanoparticles are dispersed, and the value of the surface electric potential and the concentration in nanoparticles of the second type are respectively greater than or equal to a first threshold of surface electric potential and a second threshold of concentration, the first and second thresholds depending on the nature of the second dispersion medium and of the nature of the polarizable second type nanoparticles, so that after the second contact time, the second assembly obtained is the second monolayer or multilayer assembly having the second desired geometric shape and of which at least the first layer is compact in terms of the absence of unwanted gaps of greater or equal the size of two adjacent nanoparticles of the second type, preferably the size of a nanoparticle of the second type, the nanoparticles being joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between the polarizable nanoparticles and the potential of surface of the second submotive. 6. Method of manufacturing a binary microstructure of colloidal nanoparticles according to claim 4 or claim 5, wherein the colloidal nanoparticles of the first type have the property of converting a radiation into a near infrared spectrum (NIR) into a radiation into a first visible spectrum, and nanoparticles of the second type have the property of converting the same radiation in the near infrared (NlR) spectrum into a radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum. 7. Method of manufacturing a binary micro / nano structure of colloidal nanoparticles according to any one of claims 4 to 6, wherein the concentration of charged nanoparticles of the first type, the first dispersion medium, the nanoparticles of the first type as the size, the first submotive of charges, the first contact time, the concentration of polarizable nanoparticles of the second type, the second dispersion medium, the nanoparticles of the second type in terms of size and polarizability, and the second contact time are chosen to obtain the first assembly having the first geometric shape and the second assembly having the second desired geometric shape, the first and second geometric shapes being conjugate forms and having the same height with respect to the substrate receiving surface, so that The geometric shape of the first set and the geometric shape of the second separate set are ind topographically detectable by AFM or by optical microscopy using visible spectrum illumination. 8. Method of manufacturing a micro / nano structure of colloidal nanoparticles according to any one of claims 1 to 7, wherein the step of inscription of the surface electric potential on the receiving surface of the electret substrate according to a motive of charges is optionally performed, by a procedure of sequential registration of positive and / or negative charges in the electret substrate comprised in the set consisting of an inscription of electric charges by a beam of focused ions, an inscription of electric charges by a beam of focused electrons, an inscription of electric charges by atomic force microscopy (AFM) and an inscription of electric charges by electrophotography, by a parallel registration procedure of positive and / or negative charges on the electret substrate comprised in the set formed by the electric nanoimpression and the electric microcontact. 9. Method of manufacturing a micro / nano structure of colloidal nanoparticles according to any one of claims 1 to 8, wherein The electret material is a material comprised in the group consisting of methyl polymethacrylates (PMMA), cyclic olefin copolymers (CoC), polyethylene terephthalate (PET), polydimethylsiloxanes (PDMS), polypropylenes. (PP), polycarbonates (PC), polystyrenes (PS), polyvinylchlorides (PVC), polytetrafluoroethylenes (PFT ^e ), triglycine sulfate (TGS), polyvinylidene fluoride (PVDF), silicon nitride (Si3 ^), oxide silicon (SO2), compound SiaN4 / SiO2 / Si (NOS); The substantially neutral and electrically polymerizable colloidal nanoparticles are compounds stabilized by themselves or by ligands and / or charges, which have physical properties comprised in the set formed by the plasmonic, conductive, magnetic, luminescent, catalytic, electrochromic, photochromic properties that are they have become substantially neutral and electrically polarizable, made of basic colloidal nanoparticles, the basic colloidal nanoparticles having a solid core and, optionally, a shell, and are comprised in the group consisting of latex, SO2, TO2, ZrO2; CdS, CdSe, PbSe, GaAs, GaN, InP, IN2O3, ZnS, ZnO, MoS2, Si, C, ITO, Fe2O3, Fe3O4, Co, Fe-Co, Fe3C, FesC2, Ni; Au, Ag, Cu, Pt and bimetallic nanoparticles; WO3; NaLnF4, lanthanide fluorides (LnF3), lanthanide oxides (Ln2O3), zirconates, silicates, hydroxides (Ln (OH) 3) and sulfides of oxides doped or not with one or more different lanthanides (Ln indicates a lanthanide), mixtures of these compounds and the dispersible medium of polarizable nanoparticles are optionally a liquid solvent or a non-polarizing gas, the liquid solvent being comprised in the group consisting of pentane, iso-pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclohexene, benzene, toluene, methylcyclohexane, xylene, mesitylene, chloroform, chloride methylene, tetrachlorethylene, The non-polarizing dispersant gas is included in the group consisting of N2 dinitrogen, Ar argon and air. 10. Method of manufacturing a micro / nano structure of colloidal nanoparticles according to any one of claims 1 to 9, comprising the additional steps consisting of: select and detect by spatial coordinates in the electret substrate where the assembly has been formed in a surface area not covered by the assembly in which the nanoparticles have been fixed in a random and uncontrolled manner, in the form of a structure resulting from a noise deposition, with a dense distribution in terms of compactness, random and dependent on the sample of the electret substrate on which the assembly has been formed, after capture an image of the random structure of the nanoparticles deposited in the selected surface area and form a signature, the image being optionally captured as a topographic image of AFM, an optical image or a photoluminescence image, then save the captured image and the spatial coordinates of the corresponding surface area in a memory. 11. Micro / nano structure formed by colloidal nanoparticles comprising: an electret substrate formed in an electret material and having a free reception surface in which an electrical surface potential is inscribed on the reception surface of the electret substrate according to a reason for positive and / or negative electrical charges, an assembly of colloidal nanoparticles fixed in the electret substrate, which has a geometric shape, in which colloidal nanoparticles are substantially neutral and electrically polarizable by the action of an external electric field, and The polarizable nanoparticles are arranged in monolayer or multilayer being joined directly between them and / or to the substrate by the action of dielectrophoretic forces, created by the interaction between the polarizable nanoparticles and the surface potential of the loading motif, and The reason for electric charges of the same polarity inscribed in the electret substrate corresponds to the geometric shape of the set of monolayer or multilayer nanoparticles, characterized in that the absolute value of the surface electric potential created by the motive of charges is greater than or equal to a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and so that at least the first layer of the set of nanoparticles Colloidal is compact in terms of the absence of unwanted gaps larger than the size of two adjacent nanoparticles, preferably the size of a nanoparticle. 12. Micro / nano structure formed by colloidal nanoparticles according to claim 11, wherein The absolute value of the electric surface potential created by the motive of charges is greater than or equal to a third threshold that depends on the nature of polarizable nanoparticles, and so that the assembly is multilayer. 13. Micro / nano structure formed by colloidal nanoparticles of two different types comprising in the form of a binary assembly an electret substrate formed in an electret material and having a free reception surface, a first monolayer or multilayer assembly of colloidal nanoparticles of the first type, fixed on the electret substrate, a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, fixed on the electret substrate, characterized because The electret substrate comprises an electrical surface potential inscribed on the receiving surface of the electret substrate in a predetermined motive of electric charges having a first sign and having a second sign opposite the first sign, the motive being composed of charges of a first submotive of charges of the first sign and for a second reason of charges of the second sign, and The nanoparticles of the first type that forms the first monolayer or multilayer assembly are charged either electrically according to the second sign and are joined to the electret substrate by the action of coulombian forces created by the interaction between the nanoparticles of the first type and the surface potential of the first motive of charges inscribed in the electret substrate, either substantially neutral and electrically polarizable and joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between the nanoparticles of the first type and the potential of surface of the first submotive of charges inscribed on the electrolyte substrate, and colloidal nanoparticles of the second type that form the second monolayer or multilayer assembly, are substantially neutral and electrically polarizable by the action of an external electric field, are joined together and / or to the substrate by the action of dielectrophoretic forces created from the interaction between the nanoparticles of the second type and the surface potential of the second submotive of charges inscribed in the electret substrate, and the second sub-motive of second-sign electrical charges inscribed in the electret substrate corresponds to the geometric shape of the second set of monolayer or multilayer nanoparticles, and The absolute value of the surface electric potential created by the motive of charges is greater than a first threshold of surface electric potential that depends on the nature of the polarizable nanoparticles, and such that at least the first layer of the second assembly of colloidal nanoparticles is compact in terms of the absence of unwanted gaps of sizes greater than or equal to the size of two adjacent nanoparticles, preferably the size of a nanoparticle. 14. Micro / nano structure formed by colloidal nanoparticles of two different types according to claim 13, wherein the nanoparticles of the first type and the nanoparticles of the second type respectively have a first size and a second size, and the first and second sets respectively have a first number and a second number of layers, and the product of the first number of layers by the first size and the product of the second number of layers by the second size are substantially equal, and For the first and second voltage submotive forms in terms of intensity coding, the sign of the potential on the receiving surface of the electret substrate is configured so that the first and second geometric shapes respectively of the first set and the second set they are conjugate forms and have substantially the same height with respect to the substrate receiving surface, which makes the geometric form of the first assembly and the geometric form of the second assembly undetectable separately topographically by AFM and / or by optical microscopy using illumination in the visible spectrum. 15. Micro / nano structure of colloidal nanoparticles of two different types according to claim 13 or 14, wherein the nanoparticles of the first type have the property of converting a radiation in the near infrared spectrum (NIR) into a radiation in a first visible spectrum, and the nanoparticles of the second type have the property of converting the same radiation into the near infrared spectrum ( NIR) in a radiation in a second visible spectrum, the first visible spectrum being different from the second visible spectrum. 16. Anti-counterfeiting and / or traceability and / or authentication label comprising a micro / nano colloidal nanoparticle structure defined according to any one of claims 11 to 15 or obtained by the method defined according to any one of claims 1 to 10. 17. Anti-counterfeit and / or traceability and / or authentication label according to claim 16, further comprising: a structure of nanoparticles fixed by chance and uncontrolled according to a deposition noise, with a dense distribution in terms of compactness and randomization, made in a surface area of the electret substrate not covered by the assembly, and detected in the electret substrate by spatial coordinates, and an image of said random structure of nanoparticles deposited in the marked surface area, the image being optionally captured an topographic image AFM, an optical image or a photoluminescence image, and being stored in a memory. 18. Anti-counterfeit and / or traceability and / or authentication label according to claim 17, wherein the coordinates of the image of said random structure are stored in an information medium corresponding to the image of said random structure.